The Zika virus played the role of 2016's worst health story. At the center of that story was the virus’ heartbreaking link to microcephalic babies when it infected their pregnant mothers. But sometimes, the worst vectors can still be used for good.

A team of researchers in the United States found that the Zika virus preferred killing glioblastoma stem cells—those that lead to the glioblastoma brain cancer—over regular brain cells in mice. Mice with Zika injected into their glioblastomas seemed to survive longer than those without. While mice are not humans, the researchers think they’ve found a new potential treatment option worth pursuing.

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“Genetically modified [Zika] strains that further optimize safety could have therapeutic efficacy for adult glioblastoma patients,” the researchers write in the study published today in the Journal of Experimental Medicine.

Glioblastomas are typically aggressive and malignant brain tumors that contain lots of different cell types, according to the American Brain Tumor Association. The median survival time, the amount of time after which only half of the patients survive, for patients with glioblastomas is less than two years. The researchers behind the new study note that the cells normally remain in the central nervous system, and recurrence tends to occur near the original tumor. That prompted them to look for a local therapy they can use to target specific cells—like the Zika virus.

The researchers began by injecting the Zika virus into glioblastoma stem cells taken from patients. Encouragingly, the virus seemed to stop the cells from proliferating. The virus did not infect other brain cells nearly as efficiently, according to the study. Then, the researchers grew a few different kinds of tumors in mice and injected some of them with the virus. All of the untreated mice died after 30 days in both tumor models (15 mice in one case, 7 mice in the other), but those receiving injections seemed to last days, and in some cases weeks, longer.

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While the results sound provocative, Zika is one of a few viruses researchers are pursuing to fight glioblastomas, along with measles, herpes and polio. On top of that, this is a preliminary study in a mouse model, so it’s unclear how Zika might affect real human patients. The team would like to begin human trials in the next year or two, according to the BBC.

As preliminary as results like these are, they serve as important signposts for future research. “Our work serves as a foundation for further mechanistic studies and the genetic engineering of a safe and effective [Zika virus], which could become an important tool in neuro-oncology,” the researchers wrote.